Optical filter

ABSTRACT

An optical filter includes a plurality of optical channels that each have a Fano resonance characteristic. A first optical channel, of the plurality of optical channels, is configured to pass a first portion of a first set of light beams (that are associated with a first wavelength range) and reflect a second portion of the first set of light beams when the first set of light beams falls incident on a particular surface of the first optical channel. A second optical channel, of the plurality of optical channels, is configured to pass a first portion of a second set of light beams (that are associated with a second wavelength range) and reflect a second portion of the second set of light beams when the second set of light beams falls incident on a particular surface of the second optical channel.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.17/302,810, filed May 12, 2021, which is incorporated herein byreference in its entirety.

BACKGROUND

An optical device may be utilized to capture information concerninglight. For example, the optical device may capture information relatingto a set of wavelengths associated with the light. The optical devicemay include a set of sensor elements (e.g., optical sensors, spectralsensors, and/or image sensors) that capture the information. Forexample, an array of sensor elements may be utilized to captureinformation relating to multiple wavelengths. The array of sensorelements may be associated with an optical filter. The optical filtermay include a passband associated with a first wavelength range of lightthat is passed to the array of sensor elements. The optical filter maybe associated with blocking a second wavelength range of light frombeing passed to the array of sensor elements.

SUMMARY

In some implementations, an optical filter includes a plurality ofoptical channels that includes a first optical channel and a secondoptical channel, wherein: each optical channel, of the plurality ofoptical channels, has a Fano resonance characteristic; a number ofoptical channels, of the plurality of optical channels, is greater thanor equal to five optical channels; the first optical channel isconfigured to: receive a first set of light beams associated with afirst wavelength range and a second set of light beams associated with asecond wavelength range, pass a first portion of the first set of lightbeams when the first set of light beams falls incident on at least oneof a first surface or a second surface of the first optical channel,reflect a second portion of the first set of light beams when the firstset of light beams falls incident on the first surface of the firstoptical channel, and reflect at least a portion of the second set oflight beams when the second set of light beams falls incident on thesecond surface of the first optical channel; and the second opticalchannel is configured to: receive a third set of light beams associatedwith a third wavelength range and a fourth set of light beams associatedwith a fourth wavelength range, pass a first portion of the third set oflight beams when the third set of light beams falls incident on at leastone of a first surface or a second surface of the second opticalchannel, reflect a second portion of the third set of light beams whenthe third set of light beams falls incident on the first surface of thesecond optical channel, and reflect at least a portion of the fourth setof light beams when the fourth set of light beams falls incident on thesecond surface of the first optical channel.

In some implementations, an optical filter includes a plurality ofoptical channels that includes a first optical channel and a secondoptical channel, wherein: each optical channel, of the plurality ofoptical channels, has a Fano resonance characteristic; a number ofoptical channels, of the plurality of optical channels, is greater thanor equal to a threshold number of optical channels; a first opticalchannel, of the plurality of optical channels, includes a first mirrorand a first absorber layer disposed on the first mirror; and a secondoptical channel, of the plurality of optical channels, includes a secondmirror and a second absorber layer disposed on the second mirror,wherein: the first optical channel is configured to: pass a firstportion of a first set of light beams when the first set of light beamsfalls incident on a particular surface of the first optical channel,wherein the first set of light beams is associated with a firstwavelength range, and reflect a second portion of the first set of lightbeams when the first set of light beams falls incident on the particularsurface of the first optical channel; and the second optical channel isconfigured to: pass a first portion of a second set of light beams whenthe second set of light beams falls incident on a particular surface ofthe second optical channel, wherein the second set of light beams isassociated with a second wavelength range, and reflect a second portionof the second set of light beams when the second set of light beamsfalls incident on the particular surface of the second optical channel.

In some implementations, an optical filter includes a plurality ofoptical channels that includes a first optical channel and a secondoptical channel, wherein: each optical channel, of the plurality ofoptical channels, has a Fano resonance characteristic; a number ofoptical channels, of the plurality of optical channels, is greater thanor equal to a threshold number of optical channels; the first opticalchannel is configured to: pass a first portion of a first set of lightbeams when the first set of light beams falls incident on a firstsurface of the first optical channel, wherein the first set of lightbeams is associated with a first wavelength range, and reflect a secondportion of the first set of light beams when the first set of lightbeams falls incident on the first surface of the first optical channel;and the second optical channel is configured to: pass a first portion ofa second set of light beams when the second set of light beams fallsincident on a first surface of the second optical channel, wherein thesecond set of light beams is associated with a second wavelength range,and reflect a second portion of the second set of light beams when thesecond set of light beams falls incident on the first surface of thesecond optical channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are diagrams of example configurations of an optical channeldescribed herein.

FIGS. 2A-2C are diagrams of an overview of an example implementationdescribed herein.

FIGS. 3A-3B are diagrams of an overview of an example implementationrelated to an optical channel.

FIGS. 4A-4B are diagrams of optical characteristics related to exampleimplementations described herein.

DETAILED DESCRIPTION

The following detailed description of example implementations refers tothe accompanying drawings. The same reference numbers in differentdrawings may identify the same or similar elements. The followingdescription uses a spectrometer as an example. However, the techniques,principles, procedures, and methods described herein may be used withany sensor, including but not limited to other optical sensors andspectral sensors.

A conventional optical sensor device, such as a spectrometer, may beconfigured to determine spectral information associated with light(e.g., ambient light) captured by the optical sensor device. The lightmay enter the optical sensor device and may be received by an opticalfilter and an optical sensor of the optical sensor device (e.g., whereinthe optical filter is disposed on the optical sensor). The opticalfilter may include a set of optical channels designed to respectivelypass light in different wavelength ranges to a set of sensor elements ofthe optical sensor. This allows the optical sensor to determine spectralinformation associated with the light that relates to the differentwavelength ranges.

In some cases, the conventional optical sensor device may include a beamsplitter to cause light associated with a particular wavelength range tobe split (e.g., after the light has passed through a particular opticalchannel of the optical filter) into two portions. A first portiontransmits to at least one sensor element, of the set of sensor elements,and a second portion transmits to another component of the conventionaloptical sensor device that is configured to sample one or more opticalcharacteristics of the light (e.g., without interfering withtransmission of the first portion to the at least one sensor element).However, including the beam splitter in the conventional optical sensordevice increases a complexity of the design of the conventional opticalsensor device and/or increases a size (e.g., a two-dimensional area orthree-dimensional volume) of the conventional optical sensor device,which prevents the conventional optical sensor device from beingincorporated into devices (e.g., user devices, such as a mobile phonedevices) that require a small form factor.

Some implementations described herein provide an optical filter thatincludes a plurality of optical channels that have a Fano resonancecharacteristic. For example, each optical channel, of the plurality ofoptical channels, may be configured to pass first light beams associatedwith a particular wavelength range when the first light beams fallincident on a first surface or a second surface (e.g., a top surface ora bottom surface) of the optical channel and to reflect second lightbeams associated with the particular wavelength range when the secondlight beams fall incident on the first surface (e.g., the top surface)of the optical channel. In some implementations, the optical channel maybe configured to reflect third light beams associated with a differentwavelength range when the third light beams fall incident on the secondsurface (e.g., the bottom surface) of the optical channel.

In this way, the optical filter described herein is able to pass firstportions of light associated with particular wavelength ranges and toreflect second portions of the light associated with the particularwavelength ranges. Accordingly, the optical filter provides a singlestructure that acts as an optical filter and a beam splitter. Thisreduces a need for a beam splitter in an optical sensor device (e.g.,that requires sampling of a portion of light associated with theparticular wavelength ranges) and therefore reduces a design complexityof the optical sensor device, as compared to including a separateoptical filter and a separate beam splitter. Further, this reduces asize (e.g., a two-dimensional area or three-dimensional volume) of anyoptical sensor device that includes the optical filter, which allows theoptical sensor device to be incorporated into devices (e.g., userdevices) that require a small form factor, which may not be possible fora conventional optical sensor device that includes a separate opticalfilter and a separate beam splitter.

FIGS. 1A-1B are diagrams of example configurations of an optical channel100 described herein. The optical channel 100 may be included in anoptical filter (e.g., optical filter 202 described below in relation toFIGS. 2A-2C). As shown in FIGS. 1A-1B, the optical channel 100 mayinclude a first mirror 102, a spacer 104, a second mirror 106, and/or anabsorber layer 108. As shown in FIG. 1A, the first mirror 102 and/or thesecond mirror 106 may each include a dielectric mirror. For example, thefirst mirror 102 and/or the second mirror 106 may each include a set ofalternating dielectric layers, such as an alternating set ofhydrogenated silicon layers and silicon dioxide layers. Alternatively,as shown in FIG. 1B, the first mirror 102 and/or the second mirror 106may each include a metallic mirror, such as a silver mirror.

As further shown in FIGS. 1A-1B, the spacer 104 may be disposed betweenthe first mirror 102 and the second mirror 106 (e.g., the spacer 104 maydisposed on the first mirror 102 and the second mirror 106 may bedisposed on the spacer 104). In some implementations, the spacer 104 maycomprise one or more spacer layers (e.g., as described in more detailherein in relation to FIGS. 2B-2C). In some implementations, a thicknessof the spacer 104 may be configured to provide a particular distancebetween the first mirror 102 and the second mirror 106 to cause theoptical channel 100 to pass light associated with a particularwavelength range (e.g., to pass light that has a wavelength that isgreater than or equal to a lower bound of the particular wavelengthrange and that is less than an upper bound of the particular wavelengthrange).

As further shown in FIGS. 1A-1B, the absorber layer 108 may be disposedon the second mirror 106 (e.g., a surface of the second mirror 106 thatis opposite the surface of the second mirror 106 that is disposed on thespacer 104). For example, as shown in FIGS. 1A-1B, the absorber layer108 may be disposed on a top surface of the second mirror 106.Accordingly, a surface (e.g., a top surface) of the optical channel 100may include a surface (e.g., a top surface) of the absorber layer 108.

The absorber layer 108 may include a material comprising germanium,silicon, amorphous silicon, silicon-germanium, a metallic oxide, atelluride, a sulfide, an arsenide, a phosphide, and/or an antimonide,among other examples. In some implementations, a thickness of theabsorber layer 108 may be configured to cause a portion of light thatfalls incident on the absorber layer 108 to be absorbed by the absorberlayer 108 and another portion of the light to pass through the absorberlayer 108. Additionally, or alternatively, the thickness of the absorberlayer 108 may be configured to cause the optical channel 100 to have aFano resonance characteristic. For example, when light that isassociated with a particular wavelength range falls incident on thesurface (e.g., the top surface) of the optical channel 100, the absorberlayer 108 may have a particular thickness to cause the optical channel100 to pass a first portion of the light (e.g. through the opticalchannel 100 from the top surface of the optical channel 100 to a bottomsurface of the optical channel 100) and to reflect a second portion ofthe light (e.g., at the top surface of the of the optical channel 100).In a specific example, when visible light (e.g., red-green-blue (RGB)light) falls incident on the surface (e.g., the top surface) of theoptical channel 100, the absorber layer 108 may have a particularthickness to cause the optical channel 100 to pass a first portion ofgreen light included in the visible light (e.g. through the opticalchannel 100 from the top surface of the optical channel 100 to thebottom surface of the optical channel 100) and to reflect a secondportion of the green light included in the visible light (e.g., at thetop surface of the of the optical channel 100).

In some implementations, another surface of the optical channel 100(e.g., that does not include a surface of the absorber layer 108) mayreflect light associated with one or more different wavelength ranges(e.g., that do not overlap with the particular wavelength rangedescribed above). For example, when broadband light that is associatedwith the particular wavelength range and the one or more differentwavelength ranges falls incident on the other surface (e.g., the bottomsurface) of the optical channel 100, the optical channel 100 may pass atleast a portion of light associated with the particular wavelength rangethat is included in the broadband light (e.g. through the opticalchannel 100 from the bottom surface of the optical channel 100 to thetop surface of the optical channel 100) and may reflect at least aportion of light associated with the one or more different wavelengthranges (e.g., at the bottom surface of the optical channel 100). In aspecific example, when visible light falls incident on the other surface(e.g., the bottom surface) of the optical channel 100, the opticalchannel 100 may pass at least a portion of green light included in thevisible light (e.g. through the optical channel 100 from the bottomsurface of the optical channel 100 to the top surface of the opticalchannel 100) and may reflect at least a portion of purple light (e.g., amixture of red light and blue light) included in the visible light(e.g., at the bottom surface of the of the optical channel 100).

As indicated above, FIGS. 1A-1B are provided as examples. Other examplesmay differ from what is described with regard to FIGS. 1A-1B.

FIGS. 2A-2C are diagrams of an overview of an example implementation 200described herein. As shown in FIG. 2A, example implementation 200 mayinclude an optical filter 202 that includes a plurality of opticalchannels 204 (e.g., arranged in a two dimensional array). FIG. 2A showsa top-down view of the optical filter 202. In some implementations, theoptical filter 202 may include an optical interference filter (e.g., athin film optical interference filter), a spectral filter, amultispectral filter, a bandpass filter, a blocking filter, a long-wavepass filter, a short-wave pass filter, a dichroic filter, a linearvariable filter (LVF), a circular variable filter (CVF), a Fabry-Perotfilter (e.g., a Fabry-Perot cavity filter), a Bayer filter, a plasmonicfilter, a photonic crystal filter, a nanostructure and/or metamaterialfilter, and/or an absorbent filter (e.g., comprising organic dyes,polymers, and/or glasses, among other examples), among other examples.In some implementations, as further described herein, each opticalchannel 204 has a same or similar configuration as the optical channel100 described herein in relation to FIGS. 1A-1B.

In some implementations, some or all of the plurality of opticalchannels 204 may have a Fano resonance characteristic (e.g., asdescribed herein). Further, the number of optical channels 204, of theplurality of optical channels 204, that have a Fano resonancecharacteristic may be greater than or equal to a threshold number ofoptical channels. The threshold number may be greater than or equal to,for example, 5, 10, 16, 32, 64, or 128.

FIG. 2B shows an example cross-sectional, side view of the opticalfilter 202 along the line A-A shown in FIG. 2A. As shown in FIG. 2B, aset of optical channels 204 (shown as optical channels 204-1 through204-8) may be arranged in a row (or column) adjacent to each other. Eachoptical channel 204, of the set of optical channels 204, may include asubstrate 206 (e.g., a glass substrate, or other light transmissivematerial, on which other layers described herein are grown, deposited,or otherwise formed), a first mirror 208 (e.g., that is the same as, orsimilar to, the first mirror 102 described herein in relation to FIGS.1A-1B), a set of spacer layers 210 (e.g., that is the same as, orsimilar to, the spacer 104 described herein in relation to FIGS. 1A-1B),a second mirror 212 (e.g., that is the same as, or similar to, thesecond mirror 106 described herein in relation to FIGS. 1A-1B), and/oran absorber layer 214 (e.g., that is the same as, or similar to, theabsorber layer 108 described herein in relation to FIGS. 1A-1B). Asfurther shown in FIG. 2B, the first mirror 208 may be disposed on thesubstrate 206, the set of spacer layers 210 may be disposed on the firstmirror 208, the second mirror 212 may be disposed on the set of spacerlayers 210, and/or the absorber layer 214 may be disposed on the secondmirror 212. Accordingly a surface of the absorber layer 214 (e.g., a topsurface of the absorber layer 214 as shown in FIG. 2B) may be includedin a surface of the optical channel 204 (e.g., a top surface of theoptical channel 204 as shown in FIG. 2B). The surface of the opticalchannel 204 (e.g., the top surface of the optical channel 204) may beincluded in a surface of the optical filter 202 (e.g., a top surface ofthe optical filter 202).

In some implementations, each optical channel 204, of the set of opticalchannels 204, may include a different number of spacer layers 210.Accordingly, a thickness of the set of spacer layers 210 for eachoptical channel 204 may be different, which may cause each opticalchannel 204 to be configured to pass light associated with a particularwavelength range (e.g., to pass light that has a wavelength that isgreater than or equal to a lower bound of the particular wavelengthrange and that is less than an upper bound of the particular wavelengthrange). For example, as shown in FIG. 2B, the optical channel 204-1includes a set of spacer layers 210 that includes eight spacer layers210, which causes the optical channel 204-1 to pass light associatedwith a first wavelength range; the optical channel 204-2 includes a setof spacer layers 210 that includes seven spacer layers 210, which causesthe optical channel 204-2 to pass light associated with a secondwavelength range; the optical channel 204-3 includes a set of spacerlayers 210 that includes six spacer layers 210 that causes the opticalchannel 204-3 to pass light associated with a third wavelength range;and so on.

In some implementations, a thickness of an absorber layer 214 of anoptical channel 204, of the set of optical channels 204, may match(e.g., may be the same as or within a thickness tolerance, such as 2nanometers) a thickness of an absorber layer 214 of at least one otheroptical channel 204 of the set of optical channels 204. For example, athickness of the absorber layer 214 of the optical channel 204-1 maymatch a thickness of the absorber layer 214 of the optical channel204-2. In some implementations, a thickness of an absorber layer 214 ofan optical channel 204 may be associated with a particular wavelengthrange of light that the optical channel 204 is configured to pass.Accordingly, each absorber layer 214 of the set of optical channels 204may have a different thickness than that of other optical channels 204of the set of optical channels 204. For example, a difference between athickness of an absorber layer 214 of the optical channel 204-3 and athickness of an absorber layer 214 of the optical channel 204-4 maysatisfy (e.g., may be greater than) a thickness difference threshold,such as 2 nanometers.

In some implementations, each optical channel 204, of the set of opticalchannels 204, may have a Fano resonance characteristic (e.g., due to theabsorber layer 214 being disposed on the second mirror 212 and/or asurface of the absorber layer 214 being included in a surface of theoptical channel 204). For example, each optical channel 204, of the setof optical channels 204, may be configured to pass first light beamsassociated with a particular wavelength range when the first light beamsfall incident on a first surface or a second surface (e.g., a topsurface or a bottom surface) of the optical channel 204, to reflectsecond light beams associated with the particular wavelength range whenthe second light beams fall incident on the first surface (e.g., the topsurface) of the optical channel 204, and/or to reflect third light beamsassociated with a different wavelength range when the third light beamsfall incident on the second surface (e.g., the bottom surface) of theoptical channel 204.

In an additional example, the optical channel 204-1 may be configured toreceive (e.g., on a top surface and/or a bottom surface of the opticalchannel 204-1) broadband light that includes a first set of light beamsassociated with a first wavelength range and a second set of light beamsassociated with a second wavelength range. The optical channel 204-1 maybe configured to pass a first portion of the first set of light beams(e.g., through the optical channel 204-1) when the first set of lightbeams falls incident on at least one of the top surface or the bottomsurface of the optical channel 204-1, to reflect a second portion of thefirst set of light beams (e.g., at the top surface of the opticalchannel 204-1) when the first set of light beams falls incident on thetop surface of the optical channel 204-1, and/or to reflect at least aportion of the second set of light beams (e.g., at the bottom surface ofthe optical channel 204-1) when the second set of light beams fallsincident on the bottom surface of the optical channel 204-1.Additionally, or alternatively, the optical channel 204-1 may beconfigured to prevent the second set of light beams from passing throughthe optical channel 204-1 (e.g., may be configured to block the secondset of light beams) when the second set of light beams falls incident onat least one of the top surface or the bottom surface of the opticalchannel 204-1.

As another example, the optical channel 204-2 may be configured toreceive (e.g., on a top surface and/or a bottom surface of the opticalchannel 204-2) broadband light that includes a third set of light beamsassociated with a third wavelength range and a fourth set of light beamsassociated with a fourth wavelength range. The optical channel 204-2 maybe configured to pass a first portion of the third set of light beams(e.g., through the optical channel 204-2) when the third set of lightbeams falls incident on at least one of the top surface or the bottomsurface of the optical channel 204-2, to reflect a second portion of thethird set of light beams (e.g., at the top surface of the opticalchannel 204-2) when the third set of light beams falls incident on thetop surface of the optical channel 204-2, and/or to reflect at least aportion of the fourth set of light beams (e.g., at the bottom surface ofthe optical channel 204-2) when the fourth set of light beams fallsincident on the bottom surface of the optical channel 204-2.Additionally, or alternatively, the optical channel 204-2 may beconfigured to prevent the fourth set of light beams from passing throughthe optical channel 204-2 (e.g., may be configured to block the fourthset of light beams) when the fourth set of light beams falls incident onat least one of the top surface or the bottom surface of the opticalchannel 204-2.

FIG. 2C shows another example cross-sectional, side view of the opticalfilter 202 along the line A-A shown in FIG. 2A. As shown in FIG. 2C, aset of optical channels 204 (shown as optical channels 204-1 through204-8) may be arranged in a row (or column) adjacent to each other. Eachoptical channel 204, of the set of optical channels 204, may include afirst mirror 208, a set of spacer layers 210, a second mirror 212,and/or an absorber layer 214. As further shown in FIG. 2C, the set ofoptical channels 204 may include a first subset of optical channels 204(e.g., that includes optical channels 204-1, 204-2, 204-4, 204-5, and204-7), a second subset of optical channels 204 (e.g., that includesoptical channels 204-3 and 204-6), and/or a third subset of opticalchannels 204 (e.g., that includes optical channel 204-8).

For an optical channel 204 of the first subset of optical channels 204(e.g., that includes optical channels 204-1, 204-2, 204-4, 204-5, and204-7), the set of spacer layers 210 may be disposed on the first mirror208, the second mirror 212 may be disposed on the set of spacer layers210, and/or the absorber layer 214 (e.g., absorber layer 214-1, 214-2,214-4, 214-5, or 214-7) may be disposed on the second mirror 212 (e.g.,in a similar manner as that described above in relation to FIG. 2B).Accordingly a surface of the absorber layer 214 (e.g., a top surface ofthe absorber layer 214 as shown in FIG. 2C) may be included in a firstsurface of the optical channel 204 (e.g., a top surface of the opticalchannel 204 as shown in FIG. 2C), and the first surface of the opticalchannel 204 (e.g., the top surface of the optical channel 204) may beincluded in a first surface of the optical filter 202 (e.g., a topsurface of the optical filter 202).

In this way, each optical channel 204, of the first subset of opticalchannels 204, may have a Fano resonance characteristic (e.g., due to theabsorber layer 214 being disposed on the second mirror 212 and/or thesurface of the absorber layer 214 being included in the first surface ofthe optical channel 204). For example, each optical channel 204, of thefirst subset of optical channels 204, may be configured to pass firstlight beams associated with a particular wavelength range when the firstlight beams fall incident on the first surface or the second surface(e.g., a top surface or a bottom surface) of the optical channel 204, toreflect second light beams associated with the particular wavelengthrange when the second light beams fall incident on the first surface(e.g., the top surface) of the optical channel 204, and/or to reflectthird light beams associated with a different wavelength range when thethird light beams fall incident on the second surface (e.g., the bottomsurface) of the optical channel 204.

For an optical channel 204 of the second subset of optical channels 204(e.g., that includes optical channels 204-3 and 204-6), the first mirror208 may be disposed on the absorber layer 214 (e.g., absorber layer214-3 or 214-6), the set of spacer layers 210 may be disposed on thefirst mirror 208, and/or the second mirror 212 may be disposed on theset of spacer layers 210. In this way, the second subset of opticalchannels 204 may have a different orientation (e.g., an oppositeorientation) than that of the first subset of optical channels 204.Accordingly a surface of the absorber layer 214 (e.g., a bottom surfaceof the absorber layer 214 as shown in FIG. 2C) may be included in afirst surface of the optical channel 204 (e.g., a bottom surface of theoptical channel 204 as shown in FIG. 2C), and the first surface of theoptical channel 204 (e.g., the bottom surface of the optical channel204) may be included in a second surface of the optical filter 202(e.g., the bottom surface of the optical filter 202).

In this way, each optical channel 204, of the second subset of opticalchannels 204, may have a Fano resonance characteristic (e.g., due to theabsorber layer 214 being disposed on the first mirror 208 and/or thesurface of the absorber layer 214 being included in the first surface ofthe optical channel 204). For example, each optical channel 204, of thesecond subset of optical channels 204, may be configured to pass firstlight beams associated with a particular wavelength range when the firstlight beams fall incident on the first surface or the second surface(e.g., a bottom surface or a top surface) of the optical channel 204, toreflect second light beams associated with the particular wavelengthrange when the second light beams fall incident on the first surface(e.g., the bottom surface) of the optical channel 204, and/or to reflectthird light beams associated with a different wavelength range when thethird light beams fall incident on the second surface (e.g., the topsurface) of the optical channel 204.

For an optical channel 204, of the third subset of optical channels 204(e.g., that includes optical channel 204-8), the set of spacer layers210 may be disposed on the first mirror 208, and/or the second mirror212 may be disposed on the set of spacer layers 210, and the opticalchannel 204 may not include an absorber layer 214. In this way, eachoptical channel 204, of the third subset of optical channels 204, maynot have a Fano resonance characteristic (e.g., due to an absence of anabsorber layer 214). For example, each optical channel 204, of the thirdsubset of optical channels 204, may be configured to pass first lightbeams associated with a particular wavelength range when the first lightbeams fall incident on a first surface or a second surface (e.g., a topsurface or a bottom surface) of the optical channel 204, to reflectsecond light beams associated with a different range when the secondlight beams fall incident on the first surface (e.g., the top surface)of the optical channel 204, and/or to reflect third light beamsassociated with the different wavelength range when the third lightbeams fall incident on the second surface (e.g., the bottom surface) ofthe optical channel 204.

As indicated above, FIGS. 2A-2C are provided as examples. Other examplesmay differ from what is described with regard to FIGS. 2A-2C.

FIGS. 3A-3B are diagrams of an overview of an example implementationrelated to an optical channel 300 (e.g., that corresponds to an opticalchannel 100 described herein in relation to FIGS. 1A-1B and/or theoptical channel 204 described herein in relation to FIGS. 2A-2C). Asshown in FIGS. 3A-3B, the optical channel 300 may include a substrate302 (e.g., that is the same as, or similar to, the substrate 206described herein in relation to FIG. 2B), a first mirror 304 (e.g., thatis the same as, or similar to, the first mirror 102 described herein inrelation to FIGS. 1A-1B and/or the first mirror 208 described herein inrelation to FIGS. 2B-2C), a set of spacer layers 306 (e.g., that is thesame as, or similar to, the spacer 104 described herein in relation toFIGS. 1A-1B and/or the set of spacer layers 210 described herein inrelation to FIGS. 2B-2C), a second mirror 308 (e.g., that is the sameas, or similar to, the second mirror 106 described herein in relation toFIGS. 1A-1B and/or the second mirror 212 described herein in relation toFIGS. 2B-2C), and/or an absorber layer 310 (e.g., that is the same as,or similar to, the absorber layer 108 described herein in relation toFIGS. 1A-1B and/or the absorber layer 214 described herein in relationto FIGS. 2B-2C).

As shown in FIG. 3A, a set of broadband light beams 312 may fallincident on a first surface (e.g., a top surface) of the optical channel300. The set of broadband light beams 312 may include a first set oflight beams 314 that are associated with a first wavelength range and asecond set of light beams 316 that are associated with a secondwavelength range. The optical channel 100 may be configured to passlight associated with the first wavelength range. Accordingly, theoptical channel 100 may pass a first portion of the first set of lightbeams 314-1 through the optical channel 300 from the first surface(e.g., the top surface) to a second surface (e.g., a bottom surface) ofthe optical channel 300. Further, the optical channel 300 may have aFano resonance characteristic (e.g., due to the absorber layer 310 beingdisposed on the second mirror 308 and/or a surface of the absorber layer310 being included in the first surface of the optical channel 300).Accordingly, the optical channel 300 may reflect (e.g., at the firstsurface of the optical channel 300) a second portion of the first set oflight beams 314-2.

As shown in FIG. 3B, the set of broadband light beams 312 may fallincident on the second surface (e.g., the bottom surface) of the opticalchannel 300. Accordingly, because the optical channel 100 may beconfigured to pass light associated with the first wavelength range, theoptical channel 100 may pass the first portion of the first set of lightbeams 314-1 through the optical channel 300 from the second surface(e.g., the bottom surface) to the first surface (e.g., the top surface)of the optical channel 300. Further, because the absorber layer 310 isdisposed on the second mirror 308 and not on the first mirror 304 and/orthe absorber layer 310 is included in the first surface (e.g., the topsurface) of the optical channel 300 and not in the second surface (e.g.,the bottom surface) of the optical channel 300, the optical channel 300may not exhibit the Fano resonance characteristic for light beams thatfall incident on the second surface (e.g., the bottom surface) of theoptical channel 300. Accordingly, the optical channel 300 may reflect(e.g., at the second surface of the optical channel 300) at least aportion of the second set of light beams 316.

As indicated above, FIGS. 3A-3B are provided as examples. Other examplesmay differ from what is described with regard to FIGS. 3A-3B.

FIGS. 4A-4B are diagrams 400 of optical characteristics related toexample implementations described herein. In the exampleimplementations, an optical filter (e.g., that corresponds to theoptical filter 202 described herein in relation to FIGS. 2A-2C) mayinclude a plurality of optical channels (e.g., that correspond to theoptical channel 100, the optical channel 204, and/or the optical channel300 described herein in relation to FIGS. 1A-1B, 2A-2C, and 3A-3B). Anoptical channel, of the plurality of optical channels, may include afirst surface and a second surface, where the first surface includes asurface of an absorber layer (e.g., the absorber layer 108, the absorberlayer 214, and/or the absorber layer 310 described herein in relation toFIGS. 1A-1B, 2B-2C, and 3A-3B).

FIGS. 4A-4B show a transmittance and reflectance performance ofparticular optical channels of the plurality of optical channels. Forexample, as shown in FIG. 4A and by reference number 402, a firstoptical channel, of the plurality of optical channels, may transmitgreater than approximately 10% (with a peak of approximately 15%) offirst light associated with a wavelength range between approximately 430nanometers (nm) and 480 nm that falls incident on a first surface or asecond surface of the first optical channel, and, as shown by referencenumber 404, may reflect greater than approximately 35% (with a peak ofapproximately 45%) of the first light when the first light fallsincident on the first surface of the first optical channel. As shown byreference number 406, the first optical channel may reflect less than35% (with a bottom of approximately 5%) of the first light when thefirst light falls incident on the second surface of the first opticalchannel.

As another example, as shown in FIG. 4A and by reference number 408, asecond optical channel, of the plurality of optical channels, maytransmit greater than approximately 10% (with a peak of approximately18%) of second light associated with a wavelength range betweenapproximately 530 nm and 580 nm that falls incident on a first surfaceor a second surface of the second optical channel, and, as shown byreference number 410, may reflect greater than approximately 42% (with apeak of approximately 52%) of the second light when the second lightfalls incident on the first surface of the second optical channel. Asshown by reference number 412, the second optical channel may reflectless than 40% (with a bottom of approximately 12%) of the second lightwhen the second light falls incident on the second surface of the secondoptical channel.

In an additional example, as shown in FIG. 4A and by reference number414, a third optical channel, of the plurality of optical channels, maytransmit greater than approximately 22% (with a peak of approximately29%) of third light associated with a wavelength range betweenapproximately 630 nm and 680 nm that falls incident on a first surfaceor a second surface of the third optical channel, and, as shown byreference number 416, may reflect greater than approximately 27% (with apeak of approximately 47%) of the third light when the third light fallsincident on the first surface of the third optical channel. As shown byreference number 418, the third optical channel may reflect less than42% (with a bottom of approximately 38%) of the third light when thethird light falls incident on the second surface of the third opticalchannel.

In another example, as shown in FIG. 4B and by reference number 420, afourth optical channel, of the plurality of optical channels, maytransmit greater than approximately 10% (with a peak of approximately25%) of fourth light associated with a wavelength range betweenapproximately 760 nm and 780 nm that falls incident on a first surfaceor a second surface of the fourth optical channel, and, as shown byreference number 422, may reflect greater than approximately 10% (with apeak of approximately 51%) of the fourth light when the fourth lightfalls incident on the first surface of the fourth optical channel. Asshown by reference number 424, the fourth optical channel may reflectless than 60% (with a bottom of approximately 23%) of the fourth lightwhen the fourth light falls incident on the second surface (e.g., thatdoes not include an absorber layer) of the fourth optical channel.

As indicated above, FIGS. 4A-4B are provided as examples. Other examplesmay differ from what is described with regard to FIGS. 4A-4B.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the implementations to theprecise forms disclosed. Modifications and variations may be made inlight of the above disclosure or may be acquired from practice of theimplementations.

As used herein, satisfying a threshold may, depending on the context,refer to a value being greater than the threshold, greater than or equalto the threshold, less than the threshold, less than or equal to thethreshold, equal to the threshold, not equal to the threshold, or thelike.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various implementations. In fact,many of these features may be combined in ways not specifically recitedin the claims and/or disclosed in the specification. Although eachdependent claim listed below may directly depend on only one claim, thedisclosure of various implementations includes each dependent claim incombination with every other claim in the claim set. As used herein, aphrase referring to “at least one of” a list of items refers to anycombination of those items, including single members. As an example, “atleast one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c,and a-b-c, as well as any combination with multiple of the same item.

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Further, asused herein, the article “the” is intended to include one or more itemsreferenced in connection with the article “the” and may be usedinterchangeably with “the one or more.” Furthermore, as used herein, theterm “set” is intended to include one or more items (e.g., relateditems, unrelated items, or a combination of related and unrelateditems), and may be used interchangeably with “one or more.” Where onlyone item is intended, the phrase “only one” or similar language is used.Also, as used herein, the terms “has,” “have,” “having,” or the like areintended to be open-ended terms. Further, the phrase “based on” isintended to mean “based, at least in part, on” unless explicitly statedotherwise. Also, as used herein, the term “or” is intended to beinclusive when used in a series and may be used interchangeably with“and/or,” unless explicitly stated otherwise (e.g., if used incombination with “either” or “only one of”). Further, spatially relativeterms, such as “below,” “lower,” “bottom,” “above,” “upper,” “top,” andthe like, may be used herein for ease of description to describe oneelement or feature's relationship to another element(s) or feature(s) asillustrated in the figures. The spatially relative terms are intended toencompass different orientations of the apparatus, device, and/orelement in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

What is claimed is:
 1. An optical filter, comprising: a plurality ofoptical channels that have a Fano resonance characteristic, theplurality of optical channels including: a first optical channelconfigured to: pass first light beams associated with a particularwavelength range when the first light beams fall incident on a firstsurface or a second surface of the first optical channel, and reflectsecond light beams associated with the particular wavelength range whenthe second light beams fall incident on the first surface of the firstoptical channel; and a second optical channel.
 2. The optical filter ofclaim 1, wherein the first optical channel is further configured to:reflect third light beams associated with a different wavelength rangewhen the third light beams fall incident on the second surface of thefirst optical channel.
 3. The optical filter of claim 1, wherein thefirst surface of the first optical channel is a top surface of the firstoptical channel.
 4. The optical filter of claim 1, wherein the secondsurface of the first optical channel is a bottom surface of the firstoptical channel.
 5. The optical filter of claim 1, wherein the firstoptical channel comprises: a first mirror; a set of spacer layersdisposed on the first mirror; a second mirror disposed on the set ofspacer layers; and an absorber layer disposed on the second mirror,wherein the first surface of the first optical channel comprises asurface of the absorber layer.
 6. The optical filter of claim 1,wherein: the first optical channel comprises a plurality of first layersthat includes a first absorber layer, the first surface of the firstoptical channel comprises a surface of the first absorber layer, thesecond optical channel comprises a plurality of second layers thatincludes a second absorber layer, and a first surface of the secondoptical channel comprises a surface of the second absorber layer.
 7. Theoptical filter of claim 1, wherein the first surface of the firstoptical channel and a first surface of the second optical channel areincluded in a particular surface of the optical filter.
 8. The opticalfilter of claim 1, wherein: the first surface of the first opticalchannel is included in a first surface of the optical filter, and thefirst surface of the second optical channel is included in a secondsurface of the optical filter.
 9. An optical filter, comprising: aplurality of optical channels including: a first optical channelconfigured to: pass first light beams associated with a particularwavelength range when the first light beams fall incident on a firstsurface or a second surface of the first optical channel, and reflectsecond light beams associated with the particular wavelength range whenthe second light beams fall incident on the first surface of the firstoptical channel; and a second optical channel.
 10. The optical filter ofclaim 9, wherein the first optical channel is further configured to:reflect third light beams associated with a different wavelength rangewhen the third light beams fall incident on the second surface of thefirst optical channel.
 11. The optical filter of claim 9, wherein thefirst surface of the first optical channel is a top surface of the firstoptical channel.
 12. The optical filter of claim 9, wherein the secondsurface of the first optical channel is a bottom surface of the firstoptical channel.
 13. The optical filter of claim 9, wherein the firstoptical channel comprises: a first mirror; a set of spacer layersdisposed on the first mirror; a second mirror disposed on the set ofspacer layers; and an absorber layer disposed on the second mirror,wherein the first surface of the first optical channel comprises asurface of the absorber layer.
 14. The optical filter of claim 9,wherein: the first optical channel comprises a plurality of first layersthat includes a first absorber layer, the first surface of the firstoptical channel comprises a surface of the first absorber layer, thesecond optical channel comprises a plurality of second layers thatincludes a second absorber layer, and a first surface of the secondoptical channel comprises a surface of the second absorber layer. 15.The optical filter of claim 9, wherein the first surface of the firstoptical channel and a first surface of the second optical channel areincluded in a particular surface of the optical filter.
 16. The opticalfilter of claim 9, wherein: the first surface of the first opticalchannel is included in a first surface of the optical filter, and thefirst surface of the second optical channel is included in a secondsurface of the optical filter.
 17. An optical filter, comprising: anoptical channel that has a Fano resonance characteristic, the opticalchannel being configured to: pass first light beams associated with aparticular wavelength range when the first light beams fall incident ona first surface or a second surface of the optical channel, and reflectsecond light beams associated with the particular wavelength range whenthe second light beams fall incident on the first surface of the opticalchannel.
 18. The optical filter of claim 17, wherein the optical channelis further configured to: reflect third light beams associated with adifferent wavelength range when the third light beams fall incident onthe second surface of the optical channel.
 19. The optical filter ofclaim 17, wherein the first surface of the optical channel is a topsurface of the optical channel, and wherein the second surface of theoptical channel is a bottom surface of the optical channel.
 20. Theoptical filter of claim 17, wherein the optical channel comprises: afirst mirror; a set of spacer layers disposed on the first mirror; asecond mirror disposed on the set of spacer layers; and an absorberlayer disposed on the second mirror, wherein the first surface of theoptical channel comprises a surface of the absorber layer.